IP over IPv6 Tunnels

IPv6 supports IP over IPv6 tunnels, which includes the following:

Generic routing encapsulation (GRE) IPv4 tunnel support for IPv6 traffic—IPv6 traffic can be carried over IPv4 GRE tunnels using the standard GRE tunneling technique that is designed to provide the services to implement any standard point-to-point encapsulation scheme. The primary use of GRE tunnels is for stable connections that require regular secure communication between two edge devices or between an edge device and an end system. The edge devices and the end systems must be dual-stack implementations.

GRE support over IPv6 transport—GRE has a protocol field that identifies the passenger protocol. GRE tunnels allow Intermediate System-to-Intermediate System (IS-IS) or IPv6 to be specified as a passenger protocol, which allows both IS-IS and IPv6 traffic to run over the same tunnel.

VRF-aware IPv4/IPv6 over IPv6 tunnels - Virtual Routing and Forwarding (VRF)-aware tunnels are used to connect customer networks separated by untrusted core networks or core networks with different infrastructures (IPv4 or IPv6).

Information About IP over IPv6 Tunnels

GRE IPv4 Tunnel Support for IPv6 Traffic

IPv6 traffic can be carried over IPv4 GRE tunnels using the standard GRE tunneling technique that is designed to provide the services to implement any standard point-to-point encapsulation scheme. As in IPv6 manually configured tunnels, GRE tunnels are links between two points, with a separate tunnel for each link. The tunnels are not tied to a specific passenger or transport protocol but, in this case, carry IPv6 as the passenger protocol with the GRE as the carrier protocol and IPv4 or IPv6 as the transport protocol.

The primary use of GRE tunnels is for stable connections that require regular secure communication between two edge devices or between an edge device and an end system. The edge devices and the end systems must be dual-stack implementations.

GRE Support over IPv6 Transport

GRE has a protocol field that identifies the passenger protocol. GRE tunnels allow Intermediate System-to-Intermediate System (IS-IS) or IPv6 to be specified as a passenger protocol, which allows both IS-IS and IPv6 traffic to run over the same tunnel. If GRE did not have a protocol field, it would be impossible to distinguish whether the tunnel was carrying IS-IS or IPv6 packets. The GRE protocol field makes it desirable to tunnel IS-IS and IPv6 inside GRE.

How to Configure IP over IPv6 Tunnels

The following tasks describe how to configure an IPv6 tunnel. IPv6 or IPv4 packets can be forwarded on this tunnel.

Configuring GRE IPv6
Tunnels

Perform this task
to configure a GRE tunnel on an IPv6 network. GRE tunnels can be configured to
run over an IPv6 network layer and transport IPv6 and IPv4 packets through IPv6
tunnels.

Note

You must enable IPv6 or configure IPv6 MTU size more than 1500 on a
tunnel's exit interface to avoid receiving warning messages.

Before You Begin

When GRE IPv6
tunnels are configured, IPv6 addresses are assigned to the tunnel source and
the tunnel destination. The tunnel interface can have either IPv4 or IPv6
addresses (this is not shown in the task below). The host or device at each end
of the configured tunnel must support both IPv4 and IPv6 protocol stacks.

SUMMARY STEPS

1.enable

2.configureterminal

3.interfacetunneltunnel-number

4.tunnelsource{ipv6-address |
interface-typeinterface-number}

5.tunneldestinationipv6-address

6.tunnelmodegreipv6

7.end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables
privileged EXEC mode.

Enter your
password if prompted.

Step 2

configureterminal

Example:

Device# configure terminal

Enters global
configuration mode.

Step 3

interfacetunneltunnel-number

Example:

Device(config)# interface tunnel 0

Specifies a
tunnel interface and number and enters interface configuration mode.

Step 4

tunnelsource{ipv6-address |
interface-typeinterface-number}

Example:

Device(config-if)# tunnel source ethernet 0

Specifies the
source IPv6 address or the source interface type and number for the tunnel
interface.

If an
interface type and number are specified, the interface must be configured with
an IPv6 address.

Standards and RFCs

Standard/RFC

Title

RFCs for IPv6

IPv6 RFC

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

Feature Information for IP
over IPv6 Tunnels

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.